They are awesome! Pros: Cheaper, safer for your body, eco friendly, lasts for a long time, You only need to take it out and rinse it off every 12 hours, some women experience less cramps(I didn't experience this), and personally it made me feel more empowered about my body.
cons: you need to be comfortable with getting up close and personal with your body and getting your period blood on your hands.
Overall I would highly highly recommend a menstrual cup! I love mine and I will never go back to disposable pads and tampons. I personally use a keeper cup but I hear good things about other brands like the diva cup.